Butterfly valve seal

Abstract

A valve assembly can include a valve body and a seal ring. The seal ring can be seated in a seal cavity of the valve body. The seal ring can include a base that extends in an axial direction within the seal cavity, a leg that extends from the base, and a foot that extends from the leg. When a disk of the valve assembly is in a closed valve position, a primary seal can be formed between the foot and the disk and a secondary seal is formed between the base and a first wall of the seal cavity. The seal ring can accommodate disk drift at least partly via elastic bending, and can provide disk tracking via lateral movement within the seal cavity.

1 . A valve assembly, comprising:
 a valve body;   a valve passageway extending in an axial direction through the valve body;   a disk arranged to selectively inhibit flow through the valve passageway of the valve body, the disk being movable between a valve open position and a valve closed position;   a seal cavity formed at least partly in the valve body; and   a seal ring including:
 a base extending in the axial direction within the seal cavity to provide an upstream contact structure and a downstream contact structure, relative to flow through the valve passageway along the axial direction; 
 a leg extending from the base transversely to the axial direction, from a location axially between the upstream and downstream contact structures; and 
 a foot extending transversely from a distal end of the leg, at least partly in the axial direction, 
 with the disk in the valve closed position and loaded with a first pressure from the upstream direction, a primary seal being formed between the foot of the seal ring and the disk and a secondary seal being formed between the downstream contact structure of the base of the seal ring and a downstream wall of the seal cavity. 
   
     
     
         2 . The valve assembly of  claim 1 , wherein boundaries of the seal cavity are formed by the valve body and a seal retainer, and
 wherein the secondary seal is formed between the seal retainer and the downstream contact structure of the base of the seal ring.   
     
     
         3 . The valve assembly of  claim 1 , wherein in response to disk drift when the disk is in the valve closed position and loaded with a second pressure from the upstream direction that is larger than the first pressure:
 the leg is configured to deflect relative to the base, including rotation about a first rotation point, and   the base is configured to be loaded in torsion by the leg to rotate about a second rotation point spaced apart from the first rotation point.   
     
     
         4 . The valve assembly of  claim 3 , wherein, at the first pressure, a gap is formed in the axial direction between the upstream contact structure of the base of the seal ring and an upstream wall of the seal cavity. 
     
     
         5 . The valve assembly of  claim 4 , wherein, at the second pressure, rotation of the base causes the upstream contact structure to contact the upstream wall of the seal cavity to form a tertiary seal; and
 wherein the secondary seal is radially offset from the tertiary seal.   
     
     
         6 . The valve assembly of  claim 1 , wherein the seal ring further includes a compression structure that is in biasing contact with an upstream wall of the seal cavity to urge the downstream contact structure toward the downstream wall. 
     
     
         7 . The valve assembly of  claim 6 , wherein the compression structure is a spring disposed between an upstream side of the base of the seal ring and the upstream wall of the seal cavity. 
     
     
         8 . The valve assembly of  claim 6 , wherein the compression structure is formed by a notch in the base and includes the upstream contact structure. 
     
     
         9 . The valve assembly of  claim 6 , wherein the seal ring further includes a pressure balance passageway so that a sub-volume of the seal cavity formed at a radially outward side of the seal ring is in fluid communication with an upstream side of the seal ring. 
     
     
         10 . The valve assembly of  claim 1 , wherein the base of the seal ring includes a base body and a seal member received into the base body, the seal member providing the downstream contact surface to form the secondary seal with the downstream wall of the seal cavity. 
     
     
         11 . A seal system for a butterfly valve that includes a disk and a seal ring cavity, the seal system comprising:
 a seal ring having a seal ring body, the seal ring body comprising:
 a base that extends in an axial direction between an upstream end and a downstream end and is configured to be received within the seal ring cavity; 
 a leg that extends inwardly from the base in a radial direction, to extend toward a disk of the butterfly valve from within the seal ring cavity, the leg being cantilevered relative to the base, in a cross-sectional plane that extends along the axial direction and the radial direction of the seal ring; and 
 a foot ex 
 tending from the leg in a downstream direction, opposite the base, to engage the disk of the butterfly valve to provide a primary seal when the disk is in a closed position, the downstream end of the base being configured to provide a secondary seal at a downstream wall of the seal ring cavity; and 
   the leg being flexibly supported relative to the base to permit rotation of the base upon axial loading of an upstream side of the leg, to provide a tertiary seal between the upstream end of the base and an upstream wall of the seal ring cavity.   
     
     
         12 . The seal system of  claim 11 , wherein the seal ring body is an integrally formed unitary metal body. 
     
     
         13 . The seal system of  claim 11 , wherein the downstream end of the base includes a downstream contact structure configured to provide the secondary seal; and
 wherein the upstream end of the base includes an upstream contact structure configured to provide the tertiary seal, in response to torsion loading of the base by the axial loading of the leg.   
     
     
         14 . The seal system of  claim 13 , wherein the upstream contact structure is oriented to provide the tertiary seal at a radially offset location from the secondary seal. 
     
     
         15 . The seal system of  claim 11 , wherein the seal ring body includes a passageway that fluidically couples an upstream side of the seal ring body with an outer radial side of the seal ring body. 
     
     
         16 . The seal system of  claim 11 , wherein the base includes a seal recess that receives a secondary seal insert to provide the secondary seal. 
     
     
         17 . A method of sealing a butterfly valve, the method comprising:
 rotating a disk of a butterfly valve toward a closed position so that the disk engages a foot of a seal ring, the seal ring having a base that extends in an axial direction within a seal cavity of the butterfly valve, and a leg extending from the base, the foot extending from the leg opposite the base in a downstream direction relative to flow past the disk,   applying a first upstream pressure to the disk, relative to a flow direction through the butterfly valve, so that:
 the leg deflects in the downstream direction to form a primary seal between the foot and the disk; and 
 the base is loaded by the deflection of the leg to engage a downstream wall of the seal cavity to form a secondary seal between the base and the seal cavity. 
   
     
     
         18 . The method of  claim 17 , wherein the seal ring is moveable in a radial direction to accommodate disk misalignment, the radial direction being perpendicular to the flow direction through the butterfly valve. 
     
     
         19 . The method of  claim 17 , further comprising:
 applying a second upstream pressure to the disk that is larger than the first upstream pressure, to cause the disk to drift in a downstream direction;   wherein the disk drift causes rotation of the base to engage an upstream wall of the seal cavity to form a tertiary seal between the base and the seal cavity.   
     
     
         20 . The method of  claim 19 , wherein during application of the first upstream pressure, a gap is formed between the base of the seal ring at an upstream side of the seal ring and a second wall of the seal cavity; and
 wherein the rotation of the base closes the gap to form the tertiary seal.